This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present techniques. This description is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present techniques. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.
To meet increasing energy demand, oil and gas will continue to be a major source for the energy needs of the world. Specifically, offshore hydrocarbon production is critical in meeting that growing demand. In the 1940's, offshore production began in the state of Louisiana and advancements in technology have expanded the industry into deeper waters and into more remote locations. Over the last six decades, offshore production has increased tremendously. Currently, approximately 30% of the world oil and gas production comes from offshore production and this percentage is expected to increase in the future.
During offshore hydrocarbon production, crude oil and raw natural gas produced from a well is harvested from underground reservoirs to be brought to the surface. Additional, processing may separate the raw natural gas from the crude oil. In many cases, the raw natural gas contains unacceptable levels of higher hydrocarbons, e.g., carbon dioxide (CO2), hydrogen sulfide (H2S), and other impurities, so that it cannot be burned as a fuel on the platform without initially undergoing further processing.
For example, impure concentrations of H2S or C3+ in the raw natural gas may cause corrosion and carbon build-up in most offshore production equipment. Additionally, high levels of CO2 in the raw natural gas may lower the BTU value of the fuel gas. These impurities may compromise engine operation, increase operational downtime, or emit harmful emissions into the environment. However, despite the presence of the contaminants and impurities in the raw gas that may render the use of the gas as undesirable, the raw natural gas may be the only fuel available to operate power generators, turbines, and compressor stations in remote locations and on offshore platforms. Thus, facilities to condition the raw natural gas may be implemented during offshore production.
U.S. Patent Application Publication No. 2010/0147022 by Hart et al. discloses a process for the removal of a sour species from a dehydrated natural gas feed stream. The dehydrated natural gas feed stream is cooled to conditions where a slurry of solid sour species and hydrocarbon liquids is formed together with a gaseous stream containing gaseous sour species. The gaseous stream containing gaseous sour species is then separated from the slurry and treated with a liquid solvent, thereby forming a liquid solution of the sour species and a dehydrated sweetened natural gas product stream. An apparatus for removing sour species from a dehydrated natural gas feed stream may include a vessel with a solids formation zone in fluid communication with a gas solvation zone. The solids formation zone is configured to facilitate formation of a slurry of solid sour species and hydrocarbon liquids and a gaseous stream containing gaseous sour species. The gas solvation zone is configured to facilitate formation of a liquid solution of sour species. The apparatus has an inlet for introducing the dehydrated natural gas feed stream to the solids formation zone, a conduit configured to direct the gaseous stream from the solids formation zone to the gas solvation zone, and an inlet for introducing liquid solvent into the gas solvation zone.
U.S. Pat. No. 5,718,872 to Khanmamedov discloses an apparatus for controlling the hydrogen sulfide concentration in an acid gas stream and the hydraulic loading of a sulfur recovery unit of the type having an absorber for contacting a sour gas stream with an absorbent, a regenerator for regenerating the absorbent to form an acid gas stream and a recycle system.
U.S. Pat. No. 6,551,570 to Smith et al. discloses the removal of hydrogen sulfide from gas streams by reacting the hydrogen sulfide with sulfur dioxide to produce sulfur. The reaction is effected in a reaction medium comprising a non-aqueous Lewis base with a pKb value of about 6 to about 11. The reaction medium possesses a specific combination of properties: a) absorbs sulfur dioxide and reacts chemically therewith to form a reaction product; b) absorbs hydrogen sulfide; c) removes the hydrogen sulfide from the gas stream through contact of the gas stream with the reaction medium in the presence of free sulfur dioxide, and/or the reaction product; d) acts as a catalyst for the overall reaction of the hydrogen sulfide with sulfur dioxide to produce sulfur; and e) has the capacity to absorb sulfur dioxide.
U.S. Pat. No. 7,429,287 to Frantz discloses a method and a system for sweetening a raw natural gas feed stream using a multi-stage membrane separation process. The method and system also include use of a gas turbine which operates with an impure fuel gas stream as derived from a permeate gas stream obtained in at least the second stage of a membrane separation process, or later stages if more than two stages are employed. In embodiments, the gas turbine is coupled with an electrical generator, which generates electrical power that drives a compressor for the second stage (or higher) of the membrane separation process, as well as other process equipment associated therewith, such as air coolers and process pumps. Alternatively, the gas turbine can be coupled mechanically to the compressor employed. In other embodiments, the power generated by the turbine generator combination can be exported to a local power grid. In other embodiments, the turbine generator is a micro-turbine generator (MTG) which can be used in applications where space is limited, such as an offshore platform or other oil/gas production facility or on board a floating vessel.
U.S. Pat. No. 8,298,505 to Zhai et al. discloses a process for treating a gas stream comprising hydrogen sulfide. The process includes the steps of mixing a first gas stream comprising hydrogen sulfide with a second stream comprising sulphur dioxide to produce a combined stream, whereby elemental sulphur is produced by a reaction between the hydrogen sulfide and the sulphur dioxide. The process includes the step of removing elemental sulphur, and optionally water, from the combined stream. The process also includes the step of oxidizing at least some of the elemental sulphur to form sulphur dioxide for use in the second stream, where the reaction is conducted at a temperature of from 15° C. to 155° C. and a pressure of at least 3 MPa.
Additionally, other gas treating processes may exist for the purification of gas. However, the currently available systems take up significant space and are difficult to operate in remote locations.